This application relates to a gear box trailer support. A trailer support with a two-speed gear box provides a mechanism for raising or lowering a loaded trailer using a low gear ratio which has high mechanical advantage but a relatively slow speed, or raising or lowering of an unloaded trailer, for example, using a high gear ratio which provides faster speed with lower mechanical advantage.
The two-speed gear box of conventional design effects the change between low and high ratio by axially sliding the input crank shaft manually to shift the input gear cluster attached thereto inside the gear box. Shifting this gear cluster in one direction or the other alternatively engages and disengages alternate sets of gears. This axial shifting action is made difficult by several factors: 1) there is normally a detent mechanism employed to hold the gear/shaft assembly in the desired position, so that the restraining force of the detent must be overcome in order to shift the gears; and 2) the internal parts of the gear box are normally lubricated with grease which is typically very viscous, and more so in cold weather. Because the gears of the cluster are moved during the shifting action, it is necessary for the gears to displace a quantity of grease to change position from side to side in the gear box. This produces a condition of very difficult gear shifting in cold weather and/or when the gear box is overfilled with grease.
In addition, the shifting gear cluster also imposes constraints on the gear box itself. That is, the substantial width of the gear box is dictated not just by the space required for the gears but also the added space required to shift the gears. Preferably, one set of gears must be fully disengaged before the second set can be engaged. This requires more width and results in essentially empty space inside the gear box.